From version 13 of GiD, a new system of problem types has been developed, which offers several advantages compared with the old (classic) system: it organizes better the data, provides with a more intuitive and user-friendly GUI, enable more sofisticated integration tools, etc... From this version on, this 'classic' system of problemtypes is considered deprecated, however, it is still supported by GiD.
The classic problem type system uses the files .prb, .mat, .cnd, .uni to define general properties, materials, conditions, units.
Each cathegory of data is showed in a kind of window, and materials and conditions are associated to entities.
About writting the input file for the solver, the classical approach uses simple .bas GiD templates